Bushing insulator



Jan. 2', 1945. v. HAvLlcEKA 2,366,258

BUSHING INSULATOR Filed June 15, 1940 ff "l Horraegc Patented Jan. 2, 1945 RUSHING rNsULAToa Vtzslav Havlek, Pilsen, Bohemia; vested in the Alien Property Custodian Application June 15, 1940, Serial No. 340,675. In Bohemia and Moravia October 9, 1939 1 claim. (c1. 174-31) My invention relates to bushing insulators for lead-in conductor and has for its object to provide a bushing-which would allow conduction of electric current of high voltage and intensity into a space containing a high-pressure medium. Hitherto, this object could not be achieved as the known bushings invariably failed when the task was to carry currents of high voltage and intensity into a space exposed to high-pressure e. g. such of several thousand atmospheres.

The manner in which my invention is carried out is hereinafter particularly described with reference to the accompanying drawing which represents a sectional elevation of the bushing insulator.

In the illustrated case, the interior space lled with a high-pressure medium, into which the current should be carried, is embodied directly in the bushing insulator and is indicated by letter P in the drawing. The dielectric material I of the bushing insulator is of plastic or semiplastic character (such as known under the trade name Glyptal, mycalex and the like) and contains metallic rings e. g. steel rings 2 embedded therein, the diameter and dimensions of these rings being determined by the pressure prevailing in the space P. The layers of the dielectric material I between the individual rings 2 are comparatively thin, comporting a thickness of only some tenths of millimeter up to one or more millimeters. However. it is necessary that these layers adhere perfectly to the rings 2.

The effect of this arrangement is that the stresses caused by the high pressure in the interior are carried by the metal rings 2 and the dielectric material I is relieved from these stresses, especially with view to its plastic properties.

In the direction of its longitudinal axis the bushing is clamped and rigidly held by means of nuts and bolts 3. The leak-proofness of the highpressure space P between the individual rings 2 and the dielectric layers I -is ascertained by a continuous inner layer of dielectric material which covers and adheres perfectly to the inner wall of the rings 2 and distributes evenly the inside pressure to the individual rings forming the support of this layer.

The said cylindrical inner layer may form a coherent body with the thin layer between the rings 2. The thin layers between the rings 2 may, however, be also constituted by a, material different from that which is used for the cylindrical inner layer.

The clamping force of the bolts 3 is transmitted to the bushing body by means of metallic parts 4 and insulator parts 5. The conductors or elec trcdes 6 pass through the metallic part 4 without insulation and are packed therein by a known method. The movable insert 9 exposed to the inner pressure presses the rubber packing I0 towards the ring I I, which is supported by the screw I2.

The distribution of the electric potential in the individual dielectric layers of the bushing can also be improved by electrostatic screening. Supposing e. g. that the lower electrode is connected to the earth and high potential current is brought to the upper electrode, the electrostatic screening may take the form of a conical metal screen I3 shown in dotted lines in the figure. The screen I3 is connected to the upper electrode and it distributes evenly the capacity current of the layers directed towards the earth-connected lower elec-` trodes.

The part of the bushing containing the dielectric layers as well as the screening cone may also be submerged in an oil bath in case use is made of a very high potential. Instead of the continuous conical face, separate screening rings surrounding the dielectric layers of the bushing may be used, these rings being connected electrostatically with the upper electrode and to each other and having increased diameters towards the lower end of the bushing.

The pressure medium may be admitted into the space I through the opening 8 provided in the metallic part 4. Various other apertures, such as control and pressure-gage connections may be arranged in the part 4 according to the need,

The leading-in insulator is intended for scientic investigations and measurements of the passing and quenching oi'l an electric current of very high voltage in an atmosphere of a strongly compressed gaseous medium and serves for industrial and commercial purposes.

Having now fully described my invention, I claim:

A bushing insulator for the lead-in conductor of current' of high voltage and intensity into a high-pressure space, 'comprising a hollow cylindrical body of a dielectric material possessing plastic properties at normal temperature, at metal rings embedded in said cylindrical body at small distances apart, said ilat rings having radial dimensions to resist the pressure prevailing in the interior of the bushing. n y

VITzsLAv HAVLICEK. 

